Perfluoro- and Polyfluorosulfonic Acids. 21. Synthesis of Difluoromethyl Esters Using Fluorosulfonyldifluoroacetic Acid as a Difluorocarbene Precursor

Article abstract of DOI:10.1021/jo00274a012

Difluoromethyl alkanoates 5 and fluorinated and nonfluorinated alkanesulfonates 9 were synthesized in moderate yields by the reaction of alkali metal salts of acids with fluorosulfonyldifluoroacetic acid (3) in acetonitrile under mild conditions.The presumed intermediate anion FO2SCF2CO2^- generates CF2: by elimination of SO2, CO2, and F^-.The esters are formed by insertion of CF2: into the O-H of the acid, whereas HCF3 is formed by the competing capture of F^-.Organic acids can be used indirectly in the reaction in the presence of inorganic salts such as Na2SO4 and KCl, with comparable yields of difluoromethyl esters.